Stress induced birefringence in hybrid TIR/PBG guiding solid photonic crystal fibers

Abstract

Abstract:We report on two types of polarization maintaining solid photonic crystal fibers that guide light by a combination of a photonic bandgap and total internal reflection. Group and phase birefringence are studied experimentally and numerically for stress-applying parts made from B-doped and F-doped silica. The stress field originating from Ge-doped cladding rods is shown to interfere with the stress field from the B-doped and F-doped rods. Since the differential expansion coefficients of B-doped and F-doped silica have opposite signs this interference is either destructive or constructive. Consequently, we found that the fiber with F-doped stress applying parts has the highest modal phase birefringence, and polarization cross talk is characterized by an h-parameter below 3⋅10−5 m −1 .

Intermodal and cross-polarization four-wave mixing in large-core hybrid photonic crystal fibers

“…The mechanical and optical properties used in the stress birefringence calculations are shown in Table 1. The properties shown correspond to those of pure silica and are applied identically to the Ge-doped silica regions, which is in agreement with approximations used in previous calculations of thermally induced stress birefringence [20]. Stress birefringence arises purely from the difference in the thermal expansion coefficients in the calculation, which are set to 0.4 × 10 −6 1/K and 1.7 × 10 −6 1/K for silica and the Ge-rods respectively.…”

All-solid birefringent hybrid photonic crystal fiber based interferometric sensor for measurement of strain and temperature

“…Along the direction of the SAP rods, the light is confined by TIR, while PBG confinement is working in the perpendicular direction. Thus birefringence and PBG guiding can be achieved at the same time in this hybrid fiber, which was first presented and characterized in [5]. Even though the fiber guides light by a combination of TIR and PBG mechanisms, the photonic bandgap properties are conserved, as shown in Fig.…”

“…2. As demonstrated in [5], the bandgap centered at 1050 nm has the lowest transmission loss. However, this wavelength is not compatible with modern singlemode fiber-optic sensor networks.…”

“…Wavelength (nm) 1600 As shown in Fig. 1, the all-solid birefringent hybrid PCF (NKT Photonics A/S) used in the present work has a cladding made of Ge:SiO 2 rods arranged in a triangular lattice and embedded in a background material of fused SiO 2 [5]. Two Boron-doped (B:SiO 2 ) rods are intentionally placed near the core as stress applying parts (SAPs) to introduce birefringence.…”

Transmission of a broadband light through a fiber optic loop: effect of nonlinear refractive index

“…Since the fiber loop and double loop studied were made of a fiber with weak birefringence (a fiber with stresses in the cladding area) [19] with δn ∼ (2 ÷ 5) · 10 −8 (measured in straight fiber pieces), taking into account short lengths of loops, 1 − 2 m, walk off in the phases of 2 orthogonally polarized waves may be neglected.…”